网格划分对喷雾造粒塔数值模拟精度的影响
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摘要
为了研究网格模型简化形式和网格分块策略对模拟精度的影响,对喷雾造粒塔进行了多组网格划分并将数值模拟结果与实验结果进行了对比。结果表明:采用简化的网格模型得到的模拟结果无论是数值大小还是变化趋势与实验结果偏差较大;采用无简化喷嘴网格模型(喷嘴出口网格垂直映射)得到的模拟结果有所改善,而建模时考虑了射流方向和物理耗散的无简化喷嘴网格模型得到的模拟结果效果最佳。因此在网格模型简化后需要对模拟结果进行对比验证,而且不能忽视网格分块策略对模拟精度的影响。
To study the effect of simplified geometric model and mesh generation strategy on the simulation accuracy, several groups meshing for the spray granulation is performed. Results comparison between numerical simulation and experiment is presented. It has been noticed that the simulation results obtained by simplified geometric model are much different with the experimental results. It is also found that accuracy of the simulation results obtained by using non-simplified nozzle mesh system, in which the outlet grid of the nozzles is vertically mapping, can be improved. However, the simulation results obtained by the non-simplified nozzle mesh system with the consideration of jet direction and physical dissipation are ideal. Therefore, it is necessary to verify the simulation results if a simplified model is used, and the effect of mesh generation on the accuracy of simulation results also should be considered.
To study the effect of simplified geometric model and mesh generation strategy on the simulation accuracy, several groups meshing for the spray granulation is performed. Results comparison between numerical simulation and experiment is presented. It has been noticed that the simulation results obtained by simplified geometric model are much different with the experimental results. It is also found that accuracy of the simulation results obtained by using non-simplified nozzle mesh system, in which the outlet grid of the nozzles is vertically mapping, can be improved. However, the simulation results obtained by the non-simplified nozzle mesh system with the consideration of jet direction and physical dissipation are ideal. Therefore, it is necessary to verify the simulation results if a simplified model is used, and the effect of mesh generation on the accuracy of simulation results also should be considered.
引文
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[10] CHEN S,FAN Y,YAN Z,et al.CFD simulation of gas-solid two-phase flow and mixing in a FCC riser with feedstock injection[J].Powder Technology,2016,287(1):29-42.
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[14] 王娟,毛羽,孙晓伟,等.阵列旋转式射流分布器的结构设计与实验研究[J].化工学报,2011,62(2):393-398.(WANG Juan,MAO Yu,SUN Xiaowei,et al.Design and experimental study of arraying and revolving jet flow distributor[J].Journal of Chemical Engineering of Chinese Universities,2011,62(2):393-398.)
[15] GUO B,LANGRISH T A G,FLETCHER D F.Simulation of gas flow instability in a spray dryer[J].Chemical Engineering Research & Design,2003,81(6):631-638.
[16] LANGRISH T A G,WILLIAMS J,FLETCHER D F.Simulation of the effects of inlet swirl on gas flow patterns in a pilot-scale spray dryer[J].Chemical Engineering Research & Design,2004,82(7):821-833.
[17] 冯留海,赵凡,刘美丽,等.喷嘴径向位置对喷雾造粒塔流动特性的影响[J].石油学报(石油加工),2016,32(5):1013-1019.(FENG Liuhai,ZHAO Fan,LIU Meili,et al.Effect of nozzle position on the flow behavior in a spray tower[J].Acta Petrolei Sinica(Petroleum Processing Section),2016,32(5):1013-1019.)
[18] ELSAYED K,LACOR C.Numerical modeling of the flow field and performance in cyclones of different cone-tip diameters[J].Computers & Fluids,2011,51(1):48-59.
[19] de SOUZA F J,de VASCONCELOS S R,de MORO MARTINS D A.Large eddy simulation of the gas-particle flow in cyclone separators[J].Separation and Purification Technology,2012,94:61-70.
[20] WEGNER B,MALTSEV A,SCHNEIDER C,et al.Assessment of unsteady RANS in predicting swirl flow instability based on LES and experiments[J].International Journal of Heat & Fluid Flow,2004,25(3):528-536.
[21] CUI J,CHEN X,GONG X,et al.Numerical study of gas-solid flow in a radial-inlet structure cyclone separator[J].Industrial & Engineering Chemistry Research,2010,49(11):5450-5460.Effect of Grid Generation on Simulation Accuracy of Spray Granulation TowerFENG Liuhai BU Yifeng ZHU Yanqing MAO YuLI Xi MEN ZhuowuThe simplified geometric model and mesh generation strategy have great impact on the simulation accuracy.Therefore,the jet direction and physical dissipation should be considered when building the mesh system.
[2] LI T,GEL A,PANNALA S,et al.CFD simulations of circulating fluidized bed risers,Part I:Grid study[J].Powder Technology,2014,254:170-180.
[3] VAKAMALLA T R,KUMBHAR K S,GUJJULA R,et al.Computational and experimental study of the effect of inclination on hydrocyclone performance[J].Separation & Purification Technology,2014,138:104-117.
[4] FENG L,LIU M,WANG J,et al.Study on the flow instability of a spray granulation tower[J].Separation & Purification Technology,2016,169:210-222.
[5] HONG K,CHEN S,WANG W,et al.Fine-grid two-fluid modeling of fluidization of Geldart A particles[J].Powder Technology,2016,296:2-16.
[6] AI Z T,MAK C M.Modeling of coupled urban wind flow and indoor air flow on a high-density near-wall mesh:Sensitivity analyses and case study for single-sided ventilation[J].Environmental Modelling & Software,2014,60(7):57-68.
[7] 李晓俊,袁寿其,潘中永,等.离心泵边界层网格的实现及应用评价[J].农业工程学报,2012,28(20):67-72.(LI Xiaojun,YUAN Shouqi,PAN Zhongyong,et al.Realization and application evaluation of near-wall mesh in centrifugal pumps[J].Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE),2012,28(20):67-72.)
[8] 覃文洁,胡春光,郭良平,等.近壁面网格尺寸对湍流计算的影响[J].北京理工大学学报,2006,26(5):388-392.(QIN Wenjie,HU Chunguang,GUO Liangping,et al.Effect of near-wall grid size on turbulent flow solutions[J].Transactions of Beijing Institute of Technology,2006,26(5):388-392.)
[9] HONG K,CHEN S,WANG W,et al.Fine-grid two-fluid modeling of fluidization of Geldart A particles[J].Powder Technology,2015,296(8):2-16.
[10] CHEN S,FAN Y,YAN Z,et al.CFD simulation of gas-solid two-phase flow and mixing in a FCC riser with feedstock injection[J].Powder Technology,2016,287(1):29-42.
[11] HARVIE D,LANGRISH T,FLETCHER D F.Numerical simulations of gas flow patterns within a tall-form spray dryer[J].Chemical Engineering Research and Design,2001,79(3):235-248.
[12] LIU M L,MAO Y,WANG J,et al.Dynamic simulation of flow behavior in a new spray granulation tower[J].Applied Mechanics & Materials,2012,157-158:1246-1252.
[13] 王娟,毛羽,王江云.具有离心分离功能的喷雾造粒塔:CN,2008101676764[P].2008.
[14] 王娟,毛羽,孙晓伟,等.阵列旋转式射流分布器的结构设计与实验研究[J].化工学报,2011,62(2):393-398.(WANG Juan,MAO Yu,SUN Xiaowei,et al.Design and experimental study of arraying and revolving jet flow distributor[J].Journal of Chemical Engineering of Chinese Universities,2011,62(2):393-398.)
[15] GUO B,LANGRISH T A G,FLETCHER D F.Simulation of gas flow instability in a spray dryer[J].Chemical Engineering Research & Design,2003,81(6):631-638.
[16] LANGRISH T A G,WILLIAMS J,FLETCHER D F.Simulation of the effects of inlet swirl on gas flow patterns in a pilot-scale spray dryer[J].Chemical Engineering Research & Design,2004,82(7):821-833.
[17] 冯留海,赵凡,刘美丽,等.喷嘴径向位置对喷雾造粒塔流动特性的影响[J].石油学报(石油加工),2016,32(5):1013-1019.(FENG Liuhai,ZHAO Fan,LIU Meili,et al.Effect of nozzle position on the flow behavior in a spray tower[J].Acta Petrolei Sinica(Petroleum Processing Section),2016,32(5):1013-1019.)
[18] ELSAYED K,LACOR C.Numerical modeling of the flow field and performance in cyclones of different cone-tip diameters[J].Computers & Fluids,2011,51(1):48-59.
[19] de SOUZA F J,de VASCONCELOS S R,de MORO MARTINS D A.Large eddy simulation of the gas-particle flow in cyclone separators[J].Separation and Purification Technology,2012,94:61-70.
[20] WEGNER B,MALTSEV A,SCHNEIDER C,et al.Assessment of unsteady RANS in predicting swirl flow instability based on LES and experiments[J].International Journal of Heat & Fluid Flow,2004,25(3):528-536.
[21] CUI J,CHEN X,GONG X,et al.Numerical study of gas-solid flow in a radial-inlet structure cyclone separator[J].Industrial & Engineering Chemistry Research,2010,49(11):5450-5460.Effect of Grid Generation on Simulation Accuracy of Spray Granulation TowerFENG Liuhai BU Yifeng ZHU Yanqing MAO YuLI Xi MEN ZhuowuThe simplified geometric model and mesh generation strategy have great impact on the simulation accuracy.Therefore,the jet direction and physical dissipation should be considered when building the mesh system.